Demystifying the Science and Art of Political Polling - By Mark Blumenthal

October 24, 2005

California Propositions: Pollster Showdown

MP apologizes for sparse posting over the next day or so, as his "day job" with little time for blogging.

In the meantime, readers may want to consider an emerging polling controversy in California, where pollsters have been asking about a series of ballot initiatives pushed by Governor Arnold Schwarzenegger. Three pollsters have been tracking opinions on these initiatives, the California mega-pollsters Field and the Public Policy Institute of California (PPIC) and the national pollster SurveyUSA, that as all MP readers know, conducts surveys using an automated methodology rather than live interviewers. SurveyUSA has been showing support for the initiatives running anywhere from 15 to 32 percentage points higher than the two California Pollsters. As usual, the site RealClearPolitics has an excellent compilation of results and links to the pollster releases.

Suprisingly, the proximate cause of the differences appears to come not from the mode of interviewing, but the wording of the questions. Generally, Field and PPIC are asking relatively longer questions that attempt to replicate the language that will appear on California ballots. Survey USA has been using shorter questions that attempt to boil each proposition down to a single sentence. All of this is explained in some excellent reporting and analysis by William Finn Bennett in the North County Times. Read it all.

The folks at SurveyUSA included a pollster caveat in their most recent release that discusses this issue. In an email to MP about the issue, they also disclose that they will be asking two versions of the Prop 76 quesiton on upcoming surveys:

As a result of the legitimate concerns raised by DiCamillo and others (both before this article was published, and in this article), SurveyUSA will begin doing split ballot question-wording on Proposition 76, so see what effect the addition of more words to the ballot measure description does to our poll results.

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